uglybob

hi all

a family friend has a 97 EL Gli. 100% stock, and has been pretty well looked after. she complained to me the other day that it had a really rough idle, and was stalling at lights etc (its an auto). so i said i'd have a look at it, but our friend who is a mechanic had a look - he replaced the plugs, leads & dist. cap, which 'fixed' the problem - until you drive it for long distances, when the problem starts again. small running-around it goes fine, but anything more and the problem starts again - any thoughts?

i assume based on the fact it doesn't do it all the time it isn't the base idle, or the intake manifold etc - any other thoughts?

cheers

johnydep

Sounds like this;
Idle Air Control Solenoid

The Idle Air Control Solenoid is located on the Throttle Body. The PCM uses the Idle Air Control Solenoid to move the pintle to adjust idle speed.

Battery voltage is supplied from the main relay via the idle solenoid to the PCM.
The PCM grounds this circuit to energise solenoid.
For precise control, the PCM varies the current between 0 and 1 Amps.
(By changing the Duty Cycle of a fixed Frequency Signal)

To Test Voltage:

See PCM Pin No. 21. (Use Scope to test).

Idle Speed (Base)
There are 2 different procedures for adjusting Base Idle Speed.

Procedure 1
Base Idle Speed is adjusted with the ignition timing static at TDC.
This is achieved for two minutes after the KOER self test procedure
(KOER takes 2.3 minutes to complete).

1. Ensure that the Throttle Body is clean.
2. Ensure engine is at operating temperature.
3. Carry out the KOER Self Test Procedure (2.3 minutes)
4. Insert a 0.75 mm feeler gauge between the Throttle Stop Screw and the Throttle Lever.
5. Disconnect the Idle Speed Control Solenoid.
6. Adjust Throttle Stop Adjusting Screw to achieve an idle speed of 680 to 720 RPM.
(There is only 2 minutes to complete this procedure)

Procedure 2
Base Idle Speed is adjusted with the PCM controlling ignition timing.
As the Ignition is advanced;
Idle speed is higher and there is no requirement to use a feeler gauge as above.
Adjustment time is not limited.

1. Ensure that the Throttle Body is clean.
2. Ensure engine is at operating temperature.
3. Disconnect the Idle Air Control Valve Solenoid.
4. Adjust Throttle Stop Adjusting Screw to achieve an idle speed of 680 to 720 RPM.
(No feeler gauge required as engine is not in base timing mode)

4.9 EF Futura

Howdy Fraser - welcome to the forums.

Tried an engine diagnostic?

So sounds like heat may be affecting something. As above, may be ISC but that's more likely to result in idle hunting, high revs etc. Maybe get the coil looked at - these can be affected by heat in their dying days.

__________________
1995 EF Futura: 4.9L V8 w/ Powerdyne Supercharger @ 7-8psi. Water Injection @ 3psi and above. Vortech Rising Rate FMU. 73mm C&L MAF. Shift Kit, VSS override, TCC override. Blue dash. Custom blue courtesy lights. Switched A/F meter, boost/vac and oil psi gauges. 6.5" TV, CarPC w/1500+ MP3, DVD and porn, precious porn

uglybob

hey martin - hehe cant get my FM fix for today!

yeah had been suggested it might be the coil - its the fact that it only happens when warm that threw me out. i haven't had hands on the car yet to perform a diag check or anything - as when i last drove it (be it only a short trip) the car was running fine. how much $$$ would a coil be? easy enough to replace?

4.9 EF Futura

Sorry mate havent had any experience with the 6 cylinders. Would be easy to change over but i think the manifolds on the 6 cyl make most things a bitch to access.

Makes it tough when problem only surfaces with temperature (i.e. warming the thing up every time you wanna observe it). This is why i thought coil maybe - i believe the heat and associated expansion can cause probs with them. Might be worth a search on here, lol these forums are SO huge it must have been covered before. Somewhere....

__________________
1995 EF Futura: 4.9L V8 w/ Powerdyne Supercharger @ 7-8psi. Water Injection @ 3psi and above. Vortech Rising Rate FMU. 73mm C&L MAF. Shift Kit, VSS override, TCC override. Blue dash. Custom blue courtesy lights. Switched A/F meter, boost/vac and oil psi gauges. 6.5" TV, CarPC w/1500+ MP3, DVD and porn, precious porn

uglybob

somewhere.. anywhere! lol

yeah its a pain, because it only shows up after about 45mins of driving - so taking it around the block doesn't allow anyone to narrow down the problem. will have to have a search on here, and maybe take it for a long drive to see what the issue is... bugger!